A known inkjet recording apparatus, e.g., an inkjet printer, is configured to perform printing by ejecting ink from nozzles. The inkjet printer performs printing on a recording medium by ejecting ink from an inkjet head moving in a scanning direction while feeding a recording medium, which is corrugated along the scanning direction, in a feeding direction of the recording medium perpendicular to the scanning direction.
In the known inkjet printer, gaps between the nozzles and a recording medium are greater for the nozzles on the downstream side, in the feeding direction, of the inkjet head, than for the nozzles on the upstream side of the inkjet head. To account for this, ink is configured to be ejected at different timings between the half of the nozzles of the inkjet head on the downstream side in the feeding direction and the half of the nozzles of the inkjet head on the upstream side in the feeding direction. An average value of a gap between a recording medium and the most upstream nozzle in the feeding direction and a gap between the recording medium and the most downstream nozzle in the feeding direction, among the upstream half of the nozzles, is prestored as information of a gap between a recording medium and an upstream half part of the inkjet head in the feeding direction. At the time of printing, an ejection timing (e.g., a delay time) of ink from the upstream half of the nozzles is determined based on the stored gap.
Similarly, an average value of a gap between a recording medium and the most upstream nozzle in the feeding direction and a gap between the recording medium and the most downstream nozzles in the feeding direction, among the downstream half of the nozzles, is prestored as information of a gap between a recording medium and a downstream half part of the inkjet head in the feeding direction. At the time of printing, an ejection timing (e.g., a delay time) of ink from the downstream half of the nozzles is determined based on the stored gap.